A portable electronic device can include a networking subsystem and an antenna used to communicate with a server or wireless access point. For example, these electronic devices can include a networking subsystem with a cellular network interface (UMTS, LTE, etc.), a wireless local area network interface (e.g., a wireless network such as described in the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard), and/or another type of wireless interface. In order to reduce power consumption when there is no information being wirelessly communicated, these electronic devices can transition the networking subsystem to a standby mode.
The networking subsystem can routinely re-synchronize its radio clock with the clock of the server by periodically waking up its networking subsystem and antenna (i.e., switching from a standby mode to an active mode) to receive a beacon with synchronization information (such as a timestamp) at beacon transmission times. Additionally, the networking subsystem can check a Traffic Indication Map (TIM) element for data for the electronic device that is buffered on the server. Based on the power optimization mode or communication method, the networking subsystem can consume a significant amount of power in the standby mode and/or the active mode, reducing the battery life and operating time of the electronic device.